Ward Christensen

Ward Leon Christensen (October 23, 1945 – October 11, 2024) was an American computer scientist who was the inventor of the XMODEM file transfer protocol and a co-founder of the CBBS bulletin board, the first bulletin board system (BBS) ever brought online.

Early life Christensen was born on October 23, 1945, in West Bend, Wisconsin, to Florence (née Hohmann) and Roy Christensen. His father was a safety director at West Bend Company and his mother sold World Book encyclopedias. Christensen also had a brother, Donald Christensen.

Christensen attended West Bend High School. In his senior year of high school in 1963, he created a computer that won first place in a science fair. After graduating high school, Christensen attended the University of Wisconsin–Madison before transferring to Milton College.

Career Christensen, along with collaborator Randy Suess, members of the Chicago Area Computer Hobbyists' Exchange (CACHE), started development of the first BBS during a blizzard in Chicago, Illinois, and officially established CBBS four weeks later, on February 16, 1978. CACHE members frequently shared programs and had long been discussing some form of file transfer, and the two used the downtime during the blizzard to implement it.

In 1968, Christensen was hired by IBM as a systems engineer in the sales office. In 1977, he wrote XMODEM, a protocol to send computer files over phone lines. In May 2005, Christensen and Suess were both featured in BBS: The Documentary. Christensen taught soldering techniques, until his death, through Build-a-Blinkie, a non-profit organization that hosts "learn-to-solder" events in the Great Lakes area.

Personal life Christensen lived in Dolton, Illinois, when he invented XMODEM in 1977 and co-invented CBBS in 1978. In 1993, he received the Pioneer Award from the Electronic Frontier Foundation.